地震作用下饱和土-桩-上部结构动力相互作用研究
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摘要
将土体视为液固两相多孔介质,利用连续介质力学得到了饱和土层的水平动力阻抗,将上部结构视为梁单元,桩-饱和土-桩之间的动力相互作用借助于等效的Winkler动力弹簧和波的干涉来模拟,并通过承台处力的平衡将群桩和上部结构耦合起来,研究了简谐SH地震波作用下饱和土-桩-上部结构的动力相互作用问题。以2×2群桩为例,对饱和土-桩-上部结构体系进行了数值分析,讨论有关参数对结构体系动力特性特别是抗震性能的影响。数值分析表明,桩间距、桩-土弹性模量比、长径比等对结构体系的抗震性能有较大影响。桩间距对地震放大系数的影响与外界激励的频率有关,桩土模量比较小、结构和桩基的阻尼较大时结构体系的抗震效果较好,长径比越大地震作用下产生的结构变形越大。
The soil around the pile is regarded as saturated porous medium;and the horizontal dynamic impedance of saturated soil is obtained by using continuum mechanics;and the pile-saturated soil-pile interaction is modeled with dynamic Winkler spring and wave-interference by regarding the superstructure as a beam model;through the force equilibrium at the pile cap level,the pile groups and the structure were coupled;and dynamic interaction of saturated soil-pile-structure under harmonic SH wave is also investigated.The simplest case of a 2×2 pile group is formulated;and the effect of the structural parameters on the dynamic behaviors is analyzed;especially studied the seismic properties of the saturated soil-pile structure system.Numerical calculations show that the pile spacing,length-diameter ratio,ratio of modulus between pile and soil had great effect on the dynamic behaviors of coupled system of saturated soil-pile.The influence of pile spacing on earthquake amplification coefficient is concerned with external excitation frequency;the aseismic effect is better when the ratio of modulus between pile and soil is smaller and the damping of structure and pile is larger;and the greater the length-diameter ratio,the greater the structural deformation produced by seismic action.
The soil around the pile is regarded as saturated porous medium;and the horizontal dynamic impedance of saturated soil is obtained by using continuum mechanics;and the pile-saturated soil-pile interaction is modeled with dynamic Winkler spring and wave-interference by regarding the superstructure as a beam model;through the force equilibrium at the pile cap level,the pile groups and the structure were coupled;and dynamic interaction of saturated soil-pile-structure under harmonic SH wave is also investigated.The simplest case of a 2×2 pile group is formulated;and the effect of the structural parameters on the dynamic behaviors is analyzed;especially studied the seismic properties of the saturated soil-pile structure system.Numerical calculations show that the pile spacing,length-diameter ratio,ratio of modulus between pile and soil had great effect on the dynamic behaviors of coupled system of saturated soil-pile.The influence of pile spacing on earthquake amplification coefficient is concerned with external excitation frequency;the aseismic effect is better when the ratio of modulus between pile and soil is smaller and the damping of structure and pile is larger;and the greater the length-diameter ratio,the greater the structural deformation produced by seismic action.
引文
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[9]KAYNIA A M,KAUSEL E.Dynamic stiffness and seismic response of pile groups[R].Cambridge:Massachusetts Institute of Technology,1998.
[10]GAZETAS G,MAKRIS N.Dynamical pile-soil-pile interaction I:Analysis of axial vibration[J].Earthquake Engineering and Structural Dynamics,1991,20(2):115-132.
[11]MAKRIS N,GAZETAS G.Dynamical pile-soil-pile interaction.II:Lateral and seismic response[J].Earthquake Engineering and Structural Dynamics,1992,21(2):145-162.
[12]余俊,尚守平,李忠,等.饱和土中桩水平振动引起土层复阻抗分析研究[J].岩土力学,2009,30(12):3858-3864,3870.YU Jun,SHANG Shou-ping,LI Zhong,et al.Study of resistance factor of saturated soil caused by horizontal vibration of pile[J].Rock and Soil Mechanics,2009,30(12):3858-3864,3870.
[2]WOLF J P.Dynamic soil-structure interaction[M].New Jersey:Prentice-Hall,1985.
[3]CAI Y X,GOULD P L,DESAI C S.Nonlinear analysis of 3D seismic interaction of soil-pile-structure systems and application[J].Engineering Structure,2000,22(2):191-199.
[4]GAZETAS G,FAN K,KYNIA A.Dynamic response of pile groups with different configurations[J].Soil Dynamics and Earthquake Engineering,1993,12(4):239-257.
[5]熊辉,邹银生.群桩(土)-承台,结构的动力相互作用[J].工程力学,2004,21(4):75-80.XIONG Hui,ZOU Yi-sheng.Dynamic interactive analysis of pile group-soil-structure[J].Engineering Mechanics,2004,21(4):75-80.
[6]KOO K K,CHAU K T,YANG X,et al.Soil-pile-structure interactions under SH waves[J].Earthquake Engineering and Structural Dynamics,2003,32(3):395-415.
[7]DE BOER R.Theory of porous media:Highlights in the historical development and current state[M].Berlin:Springer-Verlag,2000.
[8]YANG Xiao,CHENG Chang-jun.Gurtin variational principle and finite element simulation for dynamical problems of fluid-saturated porous media[J].Acta Mechanica Solida Sinica,2003,16(1):24-32.
[9]KAYNIA A M,KAUSEL E.Dynamic stiffness and seismic response of pile groups[R].Cambridge:Massachusetts Institute of Technology,1998.
[10]GAZETAS G,MAKRIS N.Dynamical pile-soil-pile interaction I:Analysis of axial vibration[J].Earthquake Engineering and Structural Dynamics,1991,20(2):115-132.
[11]MAKRIS N,GAZETAS G.Dynamical pile-soil-pile interaction.II:Lateral and seismic response[J].Earthquake Engineering and Structural Dynamics,1992,21(2):145-162.
[12]余俊,尚守平,李忠,等.饱和土中桩水平振动引起土层复阻抗分析研究[J].岩土力学,2009,30(12):3858-3864,3870.YU Jun,SHANG Shou-ping,LI Zhong,et al.Study of resistance factor of saturated soil caused by horizontal vibration of pile[J].Rock and Soil Mechanics,2009,30(12):3858-3864,3870.
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